High wattage high intensity lamps are used in a number of industries or activities that require a high intensity projected light. In particular, such lamps are used in high wattage theatrical and movie lamps and other high wattage lighting systems. For instance, in use as a theatrical lamp, the high intensity lamp is subjected to continuous or intermittent periods of use at full intensity and/or dimmed to the appropriate requirements of the theatrical performance. As such, in a single performance the lamp may undergo a number of heating and cooling cycles. In the movie industry, high intensity lamps tend to undergo a period of high intensity use, followed by periods of time when the lamp is not in use, e.g. until the next movie scene is to be shot. Other uses of high wattage high intensity lighting, movie and projection lamps are known.
The high wattage high intensity lamp must be connected to a power supply in a manner that will permit the changing of the lamp in the event that the bulb in the lamp burns out, referred to herein as burn out of the lamp. It is often necessary to be able to replace the high wattage high intensity lamp in a short period of time i.e. with minimal delay, so as not to unduly interrupt the shooting of a movie or the provision of appropriate lighting during a theatrical performance, or other use of the lamp. Thus, the lamp should be capable of being removed and replaced as quickly as possible.
Connection between the lamp and the source of electricity was traditionally achieved by providing cables terminating in annular connectors, also known as ring lug connectors, on both the lamp and the source of electricity i.e. the power supply. The lamp and power supply were connected by inserting a bolt through each of the annular connectors and tightening the bolt on a nut, or more commonly by screwing the bolt into a threaded orifice suitably located in the lamp system e.g. on a wall of a housing or other location. However, it was found that over a period of time, the heating and cooling of the lamp tended to loosen the bolt connection. The consequence was that the cable from the power supply tended to burn through, usually at or near the connector on that cable, and thereby disrupt the supply of electricity. This caused major problems in the use of the lighting system, and was the primary cause of the failure of the lighting system.
An improvement was made in which the cable of the power supply, also known in the industry as the ballast, was fed to and connected via a crimp joint to form a unitized assembly with a terminal block. The power supply cable was crimped into an inlet barrel that formed part of the terminal block, thereby retaining the power supply cable in the inlet of the terminal supply. Removal of the power supply cable was not intended, and the power supply cable and attached terminal block would be replaced as a unit if that should ever be necessary. The lamp was connected to the terminal block using the annular connector, which was bolted into a threaded orifice located on the terminal block.
This type of terminal block has been used with high wattage high intensity lamps for many years, and has effectively eliminated the problem of burn-through of the power supply cable. Nonetheless, a problem of premature burn-out of the high wattage high intensity lamps per se has existed, and has continued to occur from time to time. Premature burn-out is costly, as the lamps are very expensive.